1.25MHz, 400mA, High Efficiency PWM Step-Down DC/DC Converter


Update Alert Share

The RT8025 is a high-efficiency pulse-width-modulated (PWM) step-down DC-DC converter. Capable of delivering 400mA output current over a wide input voltage range from 2.5 to 5.5V, the RT8025 is ideally suited for portable electronic devices that are powered from 1-cell Li-ion battery or from other power sources within the range such as cellular phones, PDAs and handy-terminals.
Internal synchronous rectifier with low RDS(ON) dramatically reduces conduction loss at PWM mode. No external Schottky diode is required in practical application. The RT8025 automatically turns off the synchronous rectifier while the inductor current is low and enters discontinuous PWM mode. This can increase efficiency at light load condition.
The RT8025 enters Low-Dropout mode when normal PWM cannot provide regulated output voltage by continuously turning on the upper P-MOSFET. RT8025 enter shutdown mode and consumes less than 0.1μA when EN pin is pulled low.
The switching ripple is easily smoothed-out by small package filtering elements due to a fixed operation frequency of 1.25MHz. This along with small SOT-23-5 and TSOT-23-5 package provides small PCB area application. Other features include soft start, lower internal reference voltage with 2% accuracy, over temperature protection, and over current protection.


  • Cellular Telephones
  • Personal Information Appliances
  • Wireless and DSL Modems
  • MP3 Players
  • Portable Instruments
Key Spec.
Status Active
Vin (min) (V) 2.5
Vin (max) (V) 5.5
Number of Outputs 1
Vout (min) (V) 0.5
Vout (max) (V) 5.5
Output Adj. Method Fixed;Resistor
Iout (max) (A) 0.4
Current Limit (typ) (A) 1.5
Freq (typ) (kHz) 1250
Ext Sync No
Ron_HS (typ) (mOhm) 300
Ron_LS (typ) (mOhm) 250
Iq (typ) (mA) 0.05
Features 100% Duty Cycle;Current Mode Control;Enable Input;Internal Compensation;OCP;OTP;PSM;Stable with Ceramic Capacitor
Package Type TSOT-25;SOT-25
  • 2.5V to 5.5V Input Range
  • Adjustable Output From 0.5V to VIN
  • 1.0V, 1.2V, 1.3V, 1.5V, 1.8V, 2.5V and 3.3V Fixed/Adjustable Output Voltage
  • 400mA Output Current
  • 95% Efficiency
  • No Schottky Diode Required
  • 1.25MHz Fixed-Frequency PWM Operation
  • Small SOT-23-5 and TSOT-23-5 Package
  • RoHS Compliant and Halogen Free
TitleLast UpdateShareDownload
1.25MHz, 400mA, High Efficiency PWM Step-Down DC/DC Converter2008/02/04
Title Last Update ShareDownload
1.25MHz, 400mA, High Efficiency PWM Step-Down DC/DC Converter 2015/05/19
Technical Documents
TitleLast UpdateShareDownload
Power Mangement Components for Lithium-Ion Battery Powered Applications2020/12/30
TitleLast UpdateShareViews
How to estimate control loop bandwidth from the transient response time?2017/03/30 1550
Additional Documents
Title Last Update ShareDownload
Power Management Components for Lithium-Ion Battery Powered Applications